The People's Welfare question

In Chapter 1, Novak describes the two forms of modern liberal mythologoy: liberal constitutionalism and legal instrumentalism.  I confess that I did not understand what he was describing on p. 23, about legal instrumentalism.  It seemed to have something to do with an overemphasis on the economy, but otherwise I'm not sure.  Private law related somehow or was a component, but I wasn't sure what that meant either.  Is private law property and contract law?